I have a kumquat and a Mexican (or Key) lime tree in pots right next to each other. The kumquat has been flowing and fruiting like a champ nearly as long as I've owned it. The lime hasn't yet produced a mature fruit. It has flowered many times and produced little fruit the size of a lime seed. But every time each fruit falls off the branches a few days later. Both trees are on the same watering and feeding schedule, get nearly the same sun, and are subject to the same weather.
Some (possibly crackpot) theories:
Recent weather changes in Southern California are spooking the lime. (We've had hot days followed shortly by cold days. I never know if I should take a light jacket to work or not.)
The lime just isn't happy with the climate. I gather they like lots of heat.
The flowers aren't getting pollinated or are pollinated from a "bad" tree. I've seen bees working over the flowers, but I don't know if my neighbors have limes. To be safe, I self-pollinated the tree once, but no joy.
I ought to increase the watering schedule when the fruit starts to grow. Both trees are one a strict once-a-week schedule.
I'm over fertilizing the lime, which is quite a bit smaller (as it's younger) than the kumquat at this point.
Critters and birds are vandalizing my lime.
I just got a bum lime tree.
Are any of these theories likely to be the source of my problem?
(This question is about these trees for what it's worth.)
I haven't had a chance to take photos, so here are the other requested details:
The kumquat is 2+ years old and I bought the lime 1/2 a year ago. I haven't pruned either tree. Both are roughly 2 feet tall, but the kumquat is sprawling out several feet on two sides while the lime looks like Charlie Brown's Christmas tree. The dimensions of the pot are:
Outside diameter: 15"
Max. diameter inner pot: 12 ½"
Height: 12 ½"
Inside diameter: 13 ¾"
(I don't at all know what "Max. diameter inner pot" means.)